Java Spring boot Internationalization for Default Spring error messages

Question

I'm working on internationalization on an existing Spring boot project, I've been having issues trying to figure out if default spring/spring boot errors can be converted automatically.

I have it working for MethodArgumentNotValidException spring somehow converts it to the language specified in the request header

@ExceptionHandler({MethodArgumentNotValidException.class, BindException.class})
public ResponseEntity<Object> handleBadRequest(MethodArgumentNotValidException ex, WebRequest request) {
    Locale locale = request.getLocale();
    ApiResponseEnvelope envelope = new ApiResponseEnvelope(false);
    BindingResult result = ex.getBindingResult();
    List<FieldError> errors = result.getFieldErrors();

    for (FieldError err : errors) {
        ApiError ae = new ApiError(messageSource.getMessage(err, locale), 44);
        envelope.addError(ae);
    }

    return new ResponseEntity(envelope, HttpStatus.BAD_REQUEST);
}

Response:

{
    "success": false,
    "result": null,
    "errors": [
        {
            "message": "ne peut pas être nul",
            "code": 44
        },
        {
            "message": "ne peut pas être nul",
            "code": 44
        },
.
.
.

But now for other exceptions that go through the @ExceptionHandler(Exception.class) handler it returns the exception as English. I believe somehow Spring should have a way of returning these generic errors in a localized language.

Below the only way I can seem to convert an exception handled by the Exception.class handler is by reading from my messages file. Is there a way to handle these generic errors?

@ExceptionHandler(Exception.class)
public ResponseEntity<Object> handleExceptions(Exception ex, Locale locale) {
    String errorMessage = attemptToFecthMessageForCode(ex,locale);
    //messageSource.getMessage(ExceptionProperty.UNEXPECTED_ERROR.getValue(), new Object[]{ex}, locale);
    //ex.printStackTrace();
    return new ResponseEntity<>(new RestMessage(errorMessage), HttpStatus.INTERNAL_SERVER_ERROR);
}

public String attemptToFecthMessageForCode(Exception ex, Locale locale){
    String msg = ex.getMessage();
    try{
        msg = messageSource.getMessage(ex.getMessage(), ex.getStackTrace(), locale);
    }
    catch (Exception e){
        e.printStackTrace();
    }

    return msg;
}

Thanks in advance!.